Lower-limb prosthesis force and moment transducer

ABSTRACT

A computerized prosthesis alignment system includes a transducer that can measure socket reactions in the anterior/posterior plane and the right/left planes, while canceling or reducing the transverse forces on the measurements of these socket reactions. In addition, the transducer is also capable of determining the axial load or weight experienced by the prosthesis. The computerized prosthesis alignment system is in communication with a host computer. The moment data from the transducer is interpreted by the user via a computer interface. The host computer includes memory for storing one or more applications. These applications receive data from the transducer, interpret the data with discrete algebraic or fuzzy logic algorithms, and display the output numerically and graphically. Applications may also interpret the data to provide analyses to the user for aligning the prosthesis.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/843,810, filed Sep. 11, 2006, expressly incorporated by referenceherein in its entirety.

STATEMENT OF GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under Grant No. 4 R44HD47119-20 awarded by the National Institutes of Health. The U.S.Government has certain rights in the invention.

BACKGROUND

Alignment of a prosthesis is an important element of optimizing itsfunction. FIG. 1 illustrates a representative prosthesis for atranstibial amputee. The prosthesis 10 includes a foot portion 20rigidly, but adjustably, affixed to a pylon 30. The pylon 30, in turn,is connected to the prosthesis socket 60 via a tube clamp adaptor 40 anda pyramid adaptor 50. The connection between the tube clamp adaptor 40and the prosthesis socket 60 is adjustable to fix the alignment.Although not shown, the tube clamp adaptor 40 has an concave spherical,load-bearing surface on the upper end of the tube clamp adaptor 40. Thissurface includes a central hole through which the tube clamp adaptor 40receives the pyramid adaptor 50. The pyramid adaptor 50 is so namedbecause of the inverted pyramid-shaped protuberance that fits into thecentral hole of the surface in the tube clamp adaptor 40. The pyramidadaptor 50 has a convex spherical load-bearing surface designed to besupported by the concave spherical surface on the tube clamp adaptor 40that allows articulation in directions relative to the horizontal plane.In terms familiar to aviation, these are “pitch” and “roll.” Thus, thepyramid adaptor 50 can be oriented in any configuration in theanterior/posterior plane, as well as the right/left plane. The pyramidadaptor 50 is locked in place by tightening four set screws (not shown)that press against the respective four sides of the inverted pyramid.The pyramid adaptor 50 further has an upper flange that rigidly attachesto the underside of the prosthesis socket 60. In a prosthesis, thealignment of the socket 60 and pylon 30 affects the functionalperformance and comfort of the person by altering the manner in whichthe weight-bearing load is transferred between the amputated limb andthe ground.

The importance of alignment has been recognized for many decades, butlittle progress has been made to give a prosthetist the tools needed tooptimize this aspect of prosthetic care. Until now, prosthesis alignmenthas been an imprecise and inconsistent practice based primarily on thesubjective opinion and the experience of the prosthetist to visuallydetermine the proper alignment.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

In order to assist a prosthetist to optimally align a prosthesis, acomputerized prosthesis alignment system is provided that can directlymeasure prosthesis socket reactions with a transducer integrated intothe prosthesis. “Socket reactions” refer to moments experienced at theprosthesis socket 60 in the anterior/posterior plane and the right/leftplane. Another moment is experienced by the prosthesis socket 60, butwhich is not generally needed for the alignment of the prosthesis, isthe transverse force (i.e., force that tends to rotate the socket 60 inthe horizontal plane). Again, in aviation terms, this force would inducemotion referred to as “yaw”.

The computerized prosthesis alignment system includes a transducer thatcan measure the socket reactions in the anterior/posterior plane and theright/left planes, while canceling or reducing the transverse forces onthe measurements of these socket reactions. In addition, the transduceris also capable of determining the axial load or weight experienced bythe prosthesis.

The transducer is a modified pyramid adaptor that includes strain gagespositioned along anterior and posterior beams and right and left beamsthat enable measuring the anterior/posterior moment and the right/leftmoment, while canceling or reducing the transverse moments. The beamssupport the inverted pyramid, so that the forces on the pyramid aredirectly borne by the beams. A hat substantially configured to match theconcave spherical surface of the tube clamp adaptor 40 is placed overthe beams to bear the axial load.

The computerized prosthesis alignment system further includes a masterunit coupled to the transducer to enable wireless transmission of datato a host computer for processing and display of the data and also forproviding instructions for aligning the prosthesis based on the data.The master unit includes a bracket to couple the master unit to thetransducer. The master unit includes a power source, a microprocessorsystem, a serial communications bus, a serial to peripheralcommunications bus, a gyroscope, a laser line generator, a wirelesscommunications modem, and various indicator lamps and switches to enablethe methods of aligning a prosthesis.

The computerized prosthesis alignment system is in communication with ahost computer. The moment data from the transducer is interpreted by theuser via a computer interface. The host computer includes memory forstoring one or more applications. These applications are for receivingdata from the transducer, interpreting the data with discrete algebraicor fuzzy logic algorithms, and displaying the output numerically andgraphically. Applications may also interpret the data to provideanalyses to the user for aligning the prosthesis. The one or moreapplications detect the onset and cessation of walking movements,identify and enumerate gait cycles by the transitions between weightbearing and non-weight bearing actions on the transducer, index thestart and end of the stance phase of each gait cycle, mathematicallyinterpolate the data to discrete increments of stance, calculatevariables used as force moment descriptors of each resulting force andmoment waveform, label and save the stance phase normalized curves andvariables, interpret the variable values by means of algorithms tosearch for optimal values and patterns determined a priori. Theseapplications also provide a graphical user interface for initialization,orientation, numerical analysis, graphical display, alignment analysis,and digital recording of transducer data. Data may be displayed as linecharts, histograms, or numerical values. Sampled data may be compared toexpected or theoretically optimal output.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatical illustration of a prior art prosthesis;

FIGS. 2A and 2B are diagrammatical illustrations of the momentsexperienced by a prosthesis in the anterior/posterior plane;

FIGS. 3A and 3B are diagrammatical illustrations of the momentsexperienced by a prosthesis in the right/left plane;

FIG. 4 is a diagrammatical illustration of a computerized prosthesisalignment system in accordance with an embodiment of the presentinvention incorporated into a prosthesis;

FIG. 5 is a diagrammatical illustration of an exploded view of thecomputerized prosthesis alignment system of FIG. 4;

FIG. 6A is a diagrammatical illustration of a transducer in accordancewith an embodiment of the present invention;

FIG. 6B is a diagrammatical illustration of an exploded view of thetransducer of FIG. 6A;

FIG. 7 is a diagrammatical illustration of a bottom view of thetransducer of FIG. 6A;

FIG. 7A is a diagrammatical illustration of a cross-sectional view ofthe transducer of FIG. 6A;

FIG. 8 is a diagrammatical illustration of an exploded view of a masterunit in accordance with an embodiment of the present invention;

FIG. 9 is a simplified electrical schematic of the transducer of FIG.6A;

FIG. 10 is a simplified electrical schematic of the master unit of FIG.8;

FIG. 11 is a diagrammatical illustration of an environment for the useof the computerized prosthesis alignment system of FIG. 4;

FIG. 12 is a diagrammatical illustration of a computer system for usewith the computerized prosthesis alignment system of FIG. 4;

FIGS. 13-18 are flow diagrams of methods for a computerized prosthesisalignment system in accordance with one embodiment of the invention; and

FIGS. 19-32 are illustrations of a graphical user interface inaccordance with embodiments of the present invention.

DETAILED DESCRIPTION

FIGS. 2A, 2B, 3A, and 3B are intended to illustrate the momentsexperienced at the prosthesis socket 60 that affect the comfort andfunction of the prosthesis. Moments are induced at the socket 60,generally when there are unbalanced forces acting on opposite sides of atheoretical reference point 70 of the socket 60. For example, the morethe foot 20 is behind the center of rotation 70, the more that aclockwise moment in the anterior/posterior plane is experienced at thesocket 60. On the other hand, if the foot 20 is moved forward of thereference point 70, a counterclockwise moment in the anterior/posteriorplane is experienced at the socket 60. Similar forces can be experiencedin the right/left plane.

For example, referring to FIGS. 3A and 3B, the more the foot 20 is movedto the left of the reference point 70, the more a counterclockwisemoment in the right/left plane is experienced at the socket 60. On theother hand, if the foot 20 is moved to the right of the reference point70, a clockwise moment in the right/left plane is experienced at thesocket 60. These moments or socket reactions relate to what the amputeefeels and the prosthetist visually notices when dynamically aligning theprosthesis. Using the computerized prosthesis alignment system asdescribed herein, the prosthetist can gain input that is even moresensitive than the trained eye. The computerized prosthesis alignmentsystem continuously measures the moments while the amputee is walking.The computerized prosthesis alignment system includes hardware andsoftware to automatically measure and interpret the relevant momentinformation from a series of steps and provides prosthesis-specific gaitanalysis. In one embodiment for example, the moment information iscompared to a stored optimal model of alignment. A gait analysisapplication is provided that compares the real time moment informationwith the model of alignment and provides feedback on how the prosthesiscan be aligned to move closer to the model. Feedback to the prosthetistis presented in concise and easy-to-understand language and graphs. Inone embodiment, instructions are provided by the computerized prosthesisalignment system for adjusting the pyramid adaptor alignment screws insimple and explicit terms.

Referring to FIGS. 4 and 5, the computerized prosthesis alignment system100 hardware is shown integrated into a prosthesis (shown in phantomlines). The computerized prosthesis alignment system 100 includes atransducer 104 (or modified pyramid adaptor) and a master unit 106. Abracket 108 supports the master unit 106 and is used to connect themaster unit 106 to the transducer 104 in a rigid but removable manner.The computerized prosthesis alignment system software will be describedbelow in the context of applications. For ease of understanding, the useof the computerized prosthesis alignment system 100 will be described inassociation with a prosthetic limb specific for a transtibialprosthesis. However, it is to be appreciated that the computerizedprosthesis alignment system 100 may be used for other prosthesis and/orin other fields of use besides prosthesis alignment, such asorthopedics.

The transducer 104 aids, quantifies, and records prosthesis alignmentadjustments with software applications on a host computer in wirelessradio communication with the transducer 104.

In accordance with one embodiment, the transducer 104 includes a firstmajor side and a second major side. The first and second major sides,respectively, may face upwards and downwards in the prosthesis. Forpurposes of illustrating one embodiment, the major side of thetransducer 104 facing down includes an inverted pyramid 110. Theinverted pyramid 110 is a standard in the industry. In general, theinverted pyramid resembles a partial, 4-sided pyramid, wherein thesurface of each side is at an angle relative to a plane perpendicular tothe longitudinal axis of the inverted pyramid so that each side hangsover the base of the “pyramid.” The inverted pyramid 110 fits into thecentral hole of the tube clamp adaptor 40. As described in theBackground Section, the tube clamp adaptor 40 includes a concavespherical surface 114 on the upper end thereof. Four set screws 117 a,117 b, 117 c, 117 d used for fixing the position and thus, the alignmentof the prosthesis socket 60, are provided that correspond to each sidesurface of the inverted pyramid 110. The four set screws 117 a, 117 b,117 c, 117 d are threaded and pass through the tube clamp adaptor 40 soas to press against the corresponding surface of the inverted pyramid110, thus, providing a rigid but adjustable alignment. The tube clampadaptor 40 includes a concave spherical surface 114 and the transducer104 includes a corresponding convex hat 120 as load-bearing surfaces sothat the alignment between the tube clamp adaptor 40 and the transducer104 may be adjusted in the anterior/posterior plane and the right/leftplane. While the transducer 104 can be articulated in theanterior/posterior and right/left planes, rotation of the invertedpyramid 110 and transducer 104 with respect to the tube clamp adaptor 40is prevented due to the flat-sided surfaces of the inverted pyramid 110engaging the ends of the set screws 117 a, 117 b, 117 c, and 117 d.

As best seen in FIGS. 6A and 6B, wherein the transducer 104 has beeninverted for clarity, the transducer 104 includes a body having thefirst major side 112 and the second major side 114. For purposes ofrotationally aligning the transducer 104 with the prosthesis socket 60,an anterior marking notch 118 is provided, the function of which will bediscussed below. The major side 112 supports the inverted pyramid 110.In the illustration of FIGS. 6A and 6B, the inverted pyramid 110 ispointed up; however, the transducer 104 can be used in an up or downconfiguration, depending on the configuration of the prosthesis. As bestseen in FIG. 6B, the body of the transducer 104 on the major side 112supporting the inverted pyramid 110 slopes upwards to support theinverted pyramid 110. The body of the transducer 104 includes aperturesseparating the major side 112 from the inverted pyramid 110. Betweenadjacent apertures, a beam is provided that extends from the majorsurface 112 to the inverted pyramid 110. Four beams 116 a, 116 b, 116 c,and 116 d are provided that extend from the major side 112 of thetransducer 104 to the inverted pyramid 110. The arrangement of beams 116a, 116 b, 116 c, and 116 d produces a cruciform structure. The beams 116a, 116 b, 116 c, and 116 d each support a side of the inverted pyramid110. There is an anterior beam 116 a for supporting the anterior side ofthe inverted pyramid 110, a posterior beam 116 c for supporting theposterior side of the inverted pyramid 110, a left beam 116 b forsupporting the left side of the inverted pyramid 110, and a right beam116 d for supporting the right side of the inverted pyramid 110. Forpurposes of clarity, the convention as to the right and left side ismaintained from FIG. 5. As will be described further below, the beams116 a-d are able to transfer the moments acting on the prosthesis socket60 to the transducer 104 to thereby measure the anterior/posteriormoment and the right/left moment. To this end, strain gages 118 arepositioned on each side of each beam 116 a, 116 b, 116 c, and 116 dwithin the adjacent apertures.

As best seen in FIG. 7, the anterior beam 116 a includes a first 118 a(anterior-right) and second 118 b (anterior-left) strain gage attachedto each side surface of the beam 116 a. The posterior beam 116 cincludes a third 118 c (posterior-left) and fourth 118 d(posterior-right) strain gage attached to each side surface of theposterior beam 116 c. The left beam 116 b includes a fifth 118 e(left-anterior) and sixth 118 f (left-posterior) strain gage attached toeach side surface of the left beam 116 b. The right beam 116 d includesa seventh 118 g (right-posterior) and eighth 118 h (right-anterior)strain gage attached to each side surface of the right beam 116 d. Twosets of four strain gages 118 a-h are arranged into two balancedbridges, each with a passive/resistive temperature compensationcomponent in series with each bridge so as to develop a voltagerepresentative of the total bridge resistance. This voltage signal is ameasure of the axial force. The orientation of the balanced bridgesallows for calculation of moments in two orthogonal planes. The straingages 118 a-h can be semiconductor or foil strain gages. Semiconductorstrain gages are preferred for their small size and superior gagefactor, enabling a more rigid, stronger, more sensitive and more compactdesign than other types of strain gage. Titanium alloys, such asTI-6AL-4V, are preferable for their strength, good spring properties,and relatively low coefficient of thermal expansion. One embodiment of asuitable strain gage is manufactured by Micron Instruments of SimiValley, Calif., under the Model No. SS-060-033-500P. This semiconductorstrain gage is made from “p” doped bulk silicon. The strain gages arereported to have an operating strain of ±2000μ inch/inch and ±3,000μinch/inch maximum. The linearity is reported to be better than ±0.25% to600±μ inch/inch and better than ±1.5% to 1,500±μ inch/inch. The no-loadresistance of the strain gage is reported at approximately 540±50 ohmsat 78° F. The gage factor is reported to be 140±10.

FIG. 7A is a cross-sectional illustration of the transducer 104 of FIG.7. The left beam 116 b and the right beam 116 d are visible supportingthe inverted pyramid 110 from the base. The beams 116 b and 116 d areformed from and rise from the major side 112 of the transducer 104. Thebeams 116 a-d raise the inverted pyramid 110 above the surface of majorside 112 of the transducer 104.

Referring back to FIG. 6B, a load-bearing hat 120 having a convexspherical surface to match with the tube clamp adaptor 40 is placed overthe beams 116 a-d. The upper inner diameter of the hat 120 rests on alip 124 below the inverted pyramid 110 and above the individual beams116 a-d. The body of the hat 120 being clamped between the tube clampadaptor 40 and the inverted pyramid 110, transfers the prosthesis socket60 reaction forces to the beams 116 a-d, including theanterior/posterior and right/left moments. An O-ring seal 122 placedbetween the hat 120 and the major side 112 prevents dirt and othercontamination from entering the inside of the transducer 104 that housesthe electronic components. The transverse moments can be canceled, or atleast reduced, by arranging the strain gages so that a transverse momentsensed by any strain gage is canceled by an oppositely placed straingage. The beams 116 a-d being joined to the inverted pyramid 110 that,in turn, is in contact with the four set screws 117 a-d permits thetransfer of the anterior/posterior moment and right/left moment to thebeams 116 a-d. Any anterior and/or posterior moment and any right and/orleft moment are transferred from the inverted pyramid 110 to the beams116-116 d wherein the stresses (compression and tension) are sensed bythe strain gages 118 a-h. The arrangement of strain gages 118 a, 118 b,118 c, 118 d, 118 e, 118 e, 118 f, 118 g, and 118 h allowsdifferentiation between anterior/posterior and right/left directions ofthe moments and cancels transverse plane moments. The load-bearing hat120 receives the axial force or weight and transfers the weight onto thelip 124 above the beams. The beams 116 a, 116 b, 116 c, and 116 dreceive the axial force and respond by compressing, which is sensed bythe strain gages 118 a, 118 b, 118 c, 118 d, 118 e, 118 f, 118 g, and118 h.

In an alternate embodiment, strain gages 118 a-118 h may be combineddifferently, or switched electrically with electronic switchingelements, such as analog switches, into circuit patterns sensitive tomoments in the transverse plane, while rejecting moments in the otherorthogonal planes. For example, if strain gages 118 d and 118 a areswapped, anterior/posterior moments would be substantially rejected andtransverse moments about the axis of the transducer 104 would be sensed.In an embodiment wherein electronic switching of the strain gages'combination is employed, the transducer 104 may be dynamicallyreconfigured by software to selectively sense or reject moments in anyof the three orthogonal planes. Other embodiments may employ circuitsother than the Wheatstone bridge arrangement shown in FIG. 9. Forexample, each strain gage may be part of a simple voltage dividernetwork. In this embodiment, the voltage resulting across the straingage would be amplified and converted to a digital value as describedbelow. This scheme allows capture of raw data representative of momentsin all three planes, axial and shear forces, all concurrently andwithout the need to reconfigure bridge circuits, requiring software tocombine and analyze the values from each strain gage.

Referring still to FIG. 6B, four bolt slots 126 traverse the transducerbody from one major side 112 to the second and opposite major side 114for receiving bolts to attach the transducer 104 to the bottom of theprosthesis socket 60. The right side and left side of the transducerbody include an elongated slot 128 extending from the anterior to theposterior side. The distance between the slot on the right and leftsides corresponds to the spacing between two prongs of the bracket 108that are used for connecting the transducer 104 to the master unit 106.

On the major side 114 opposite to the side 112 containing the invertedpyramid 110, a cavity is provided in the body of the transducer 104 forthe inclusion of various electronic components. A printed circuit board130 holds the electronic components. The printed circuit board 130includes circuits for signal conditioning, temperature compensation,analog-to-digital conversion, digital-to-analog conversion and a serialcommunication bus. Additionally, transducer calibration data are storedin an onboard memory. The memory may also serve to record data over anextended period of time, such as when a patient wears the prosthesis inthe normal course of a day. Records of alignment analysis and otherpatient treatment data may also be stored in the onboard memory. Powerto the transducer 104 and wireless telemetry of the transducer 104output are provided for by the master unit 106. An input/output (I/O)connector 202 is provided at the posterior side of the printed circuitboard 130 for receiving a communication plug 264 from the master unit106. A simplified schematic diagram of the electrical components of thetransducer 104 is provided in FIG. 9. Retaining cover 134 is providedadjacent to the printed circuit board 130. Retaining cover 134 iscovered with an adhesive-backed insulating ID label 136. A hollow pin138 traverses the centers of the printed circuit board 130 and theretaining cover 13, and is anchored in the transducer 104 body, thusanchoring these components and allowing clearance for socket linerlocking pins. A dummy plug 140 can be inserted into the I/O connector202 when not connected to the master unit 106 for preventing debris toenter and do damage to the components in the body of the transducer 104.

Referring to FIG. 8, the master unit 106 is illustrated. The master unit106 includes the bracket 108 having a platform with details to providefor the support of the various components of the master unit 106. Thebracket 108 has a first and second major side corresponding with the upand down direction. The bracket 108 includes a posterior platform thatsupports the master unit's 106 components. The bracket 108 includes afirst and second prong 140 a, 140 b disposed on the anterior side. Thespacing between the first and second prongs 140 a, 140 b matches thewidth of the transducer body at the slots 128 described above. On theunderside of the bracket's 108 posterior platform, two rechargeablepower units 250 a, 250 b, such as batteries, are provided. The batteries250 a, 250 b are supported by a lower housing member 146 held to thebracket's 108 posterior platform via a screw 148. On the upper side ofthe bracket's 108 posterior platform, a printed circuit board 144 isprovided for electrical components. A simplified schematic of the masterunit's 106 components is provided in FIG. 10. The printed circuit 144board supports a laser light line generator 254, status indicator lamps262, a central processing unit 154, a gyroscope 258, and an input/outputconnector 264 that can be a plug, for example. The printed circuit board144 is housed between the bracket's 108 posterior platform and the upperhousing member 162.

Referring to FIG. 9, a schematic diagram showing the electricalcomponents and configuration of the transducer 104 is provided. Thetransducer 104 includes an input/output connector 202 that can be ajack, for example. The input/output connector 202 receives voltage froma power source, such as the batteries 250 a,b in the master unit 106.The voltage output from the master unit 106 is regulated by the voltageregulator 200 in the transducer 104. The input/output connector 202 isconnected to power and a communication bus 204. The transducer 104includes a temperature sensor 206. The temperature sensor 206 can be athermistor that responds to changes in temperature by experiencing achange in resistance. The transducer 104 includes a memory 208. Thememory 208 can be any volatile or non-volatile memory, such as, but notlimited to PROM, EEPROM, Flash, DRAM, eDRAM, and PROM to name a fewrepresentative examples. The memory 208 holds transducer calibrationdata and alternatively, the memory 208 may hold data that is recordedover an extended period of time. Memory 208 may serve to record dataover an extended period of time, such as when a patient wears theprosthesis in the normal course of a day. Records of alignment analysisand other patient treatment data may also be stored in the onboardmemory 208. The transducer 104 includes digital-to-analog conversioncircuit 210. The transducer 104 includes analog-to-digital conversioncircuit 212. The transducer 104 includes various signal conditioningamplification circuits 214, 216, and 218. The temperature sensor 206,memory 208, digital-to-analog conversion circuit 210, andanalog-to-digital conversion circuit 212 are connected to power and thecommunication bus 204. The eight strain gages 118 a-118 h are arrangedinto balanced bridge circuits 220 and 222. Each balanced bridge circuit220 and 222 is connected to the voltage regulator 200.

Regulated voltage is applied through resistor 224 (R₁) to the balancedbridge circuit 220. Resistor 224 compensates for temperature effects onthe strain gages 118 e, 118 h, 118 f, and 118 g to correct thedifferential output voltage for the right/left moment. The balancedbridge circuit 220 is connected to ground potential. The voltagedifferential output of the balanced bridge circuit 220 is amplified bythe amplification circuit 214. The amplification circuit 214 is furtherconnected to the voltage regulator 200. The amplification circuit 214 isfurther connected to ground potential. The output of the amplificationcircuit 214 is sent to the analog-to-digital conversion circuit 212.

Regulated voltage is applied through resistor 226 (R₂) to the balancedbridge circuit 222. Resistor 226 compensates for temperature effects onthe strain gages 118 d, 118 a, 118 c, 118 b to correct the differentialoutput voltage for the anterior/posterior moment. The balanced bridgecircuit 222 is connected to ground potential. The voltage differentialoutput from the balanced bridge circuit 222 is amplified by theamplification circuit 218. The amplification circuit 218 is similarlyconnected to the voltage regulator 200 and to ground potential. Theoutput from the amplification circuit 218 is sent to theanalog-to-digital conversion circuit 212.

The four strain gages 118 e, 118 h, 118 f, and 118 g are for measuringthe right/left moments and are arranged into the first balanced bridgecircuit 220. The voltage regulator 200 supplies power to the balancedbridge 220 via the resistor 224 (R₁) at a point between strain gages 118e and 118 g. The ground or lower potential is at a point between straingage 118 h and strain gage 118 f. A strain in the right/left planeresults in a voltage difference measured between a point (R) locatedbetween strain gage 118 g and strain gage 118 f and a point (L) locatedbetween strain gage 118 e and strain gage 118 h. The voltage difference(R−L) output from the balanced bridge 220 is linearly related to thestrain applied in the right/left plane and direction. For example, apush on the left side of the foot 20 stretches gages 118 e and 118 f andcompresses gages 118 h and 118 g. The moment in the right/left plane isdirectly proportional to the voltage at R minus the voltage at L (the“RL” voltage) which is a positive number (and generates positive A/Dcounts). Gages 118 c and 118 b in the other bridge 222 may also beminimally stretched while gages 118 d and 118 a may be minimallycompressed. This results in a nominal zero anterior/posterior output. Asimilar, but opposite effect is produced if the push is on the rightside of the foot 20. The output voltage from the balanced bridge circuit220 is amplified by an amplification circuit 214.

The four strain gages 118 d, 118 a, 118 c, and 118 b are for measuringthe anterior/posterior moments and are arranged into the second balancedbridge circuit 222. The voltage regulator 200 supplies power to thebalanced bridge circuit 222 via the resistor 226 (R₂) at a point betweenstrain gages 118 d and 118 b. The ground or lower potential is at apoint between strain gage 118 a and strain gage 118 c. A strain in theanterior/posterior plane results in a voltage difference measuredbetween a point (A) located between strain gage 118 b and strain gage118 c and a point (P) located between strain gage 118 d and strain gage118 a. The voltage difference (A−P) output from the balanced bridgecircuit 222 is linearly related to the strain applied in theanterior/posterior plane and direction. For example, a push on the heelof the foot stretches gages 118 c and 118 d and compresses gages 118 aand 118 b. The moment in the anterior/posterior plane is directlyproportional to the voltage at A minus the voltage at P (the “AP”voltage) which is a positive number (and generates positive A/D counts).Gages 118 f and 118 g in the other bridge 220 may also be minimallystretched while gages 118 e and 118 h may be minimally compressed. Thisresults in a nominal zero right/left output. A similar, but oppositeeffect is produced if the push is on the toe side of the foot 20. Theoutput voltage from the balanced bridge circuit 222 is amplified by anamplification circuit 218.

The anterior/posterior and right/left signals generated by thetransducer 104 are proportional to bending moments orthogonal withrespect to the geometry of the transducer 104. For the signals to beuseful for alignment of the prosthesis however, it is preferable thatthe transducer 104 also be aligned with a patient's line of progressionas he/she walks, such that, for example, a moment at the base of theprosthesis socket 60, purely in the direction of the patient's motionwill produce a corresponding transducer output indicating ananterior/posterior moment, and no right/left output, whereas if thetransducer 104 were rotated relative to the line of progression anerroneous signal would be present in the right/left output and theanterior/posterior output would be reduced correspondingly. Thecomputerized prosthesis alignment system 100 provides for a correctionfactor that takes into account a yaw angle deviation from a true line ofprogression. This correction factor is implemented by a computerapplication as will be described below. The transducer's 104 mountingslots 128 generally permit a posterior orientation adjustment to preventthe master unit 106 from hitting the other leg when walking.

Additional connections are established to measure the axial loadexperienced by the combined strain gages 118 a, 118 b, 118 c, 118 d, 118e, 118 f, 118 g, and 118 h. The voltage to the balanced bridge circuit220 after the resistor 224 (the “Axial 1” voltage) is averaged with thevoltage of the balanced bridge circuit 222 after the resistor 226 (the“Axial 2” voltage). The Axial 1 voltage and Axial 2 voltage result fromthe voltage division of the source voltage by fixed resistors 224 (R₁)and 226 (R₂) and the algebraic sums of the voltages of the strain gages118 e, 118 h, 118 f, 118 g and 118 d, 118 a, 118 c, and 118 b,respectively. The Axial 1 voltage and the Axial 2 voltage areelectrically independent of differential voltages RL and AP. Theaveraged axial voltage signal at AX (FIG. 9) is not temperaturecompensated; however, compensation is done in software by monitoringtransducer temperature with the temperature sensor 206 and applying anappropriate gain coefficient stored in memory 208. Resistors 228 (RS₁)and 230 (RS₂) are significantly larger than the strain gage resistancesso as to have negligible effects on the voltage measurement at thebridges 220 and 222. The averaged voltage AX is amplified by theamplification circuit 216. This voltage represents the net axial load onthe strain gages 118 a-118 h. The amplification circuit 216 is connectedto the voltage regulator 200 and to ground potential. The output fromthe amplification circuit 216 is sent to the analog-to-digitalconversion circuit 212. This voltage is a measure of the net axial forceon the transducer 104, from which the weight of the patient can beextracted. Increasing the axial compression load results in negativevoltage change and negative A/D counts. The output, however, may not belinear. A correction is done in software based on calibration datastored in memory 208.

Each of the amplification circuits 214, 216, and 218 mentioned above isfurther connected to the digital-to-analog conversion circuit 210. Theanalog-to-digital conversion circuit 212, the digital-to-analogconversion circuit 210, the memory 208, and the temperature sensor 206are further connected to the communications bus 204. The transducer 104includes a data communications protocol. In one embodiment, the datacommunications protocol is the I²C serial communication protocol forcommunication between the transducer 104 and master unit 106.

A further response is experienced on the axis of the inverted pyramid110 that is the result of moment in the plane horizontal to the ground,or the transverse moment. In response to moment in this direction,strain gages 118 e, 118 g, 118 a, and 118 c are stressed in onedirection while gages 118 h, 118 f, 118 d, and 118 b are stressedequally but in the opposite direction. The strain gages have beenarranged to substantially cancel the response from moment in thetransverse plane. This results in nominally zero outputs in the AP andRL voltages.

Trimmer resistors or potentiometers may be used to cancel out minorvariations between the multiplicity of strain gages and balance thebridge circuits 220 and 222. However, the use of such resistors orpotentiometers can be avoided by compensating for the offset in thebridge circuits' 220 and 222 output by varying the offset input to theamplification circuits 214, 216, and 218, including centering theamplification circuits' 214, 216, and 218 output in the range of theanalog-to-digital conversion circuit 212. This is accomplished by thedigital-to-analog conversion circuit 210 at the time when the system is“zeroed” under software control by reading the output value of theamplification circuits 214, 216, and 218 and adjusting the offset inputby a corresponding value so as to achieve zero output. This has theadvantage that the number of components is reduced, space and labor areconserved, dynamic range is maximized, and runtime calibration of thetransducer 104 is permitted without physical disassembly or physicaladjustment and allows the transducer 104 to be a substantiallypermanently sealed assembly.

Referring to FIG. 10, the components of the master unit 106 areschematically illustrated. The master unit 106 includes a power supply250, such as one or more batteries, coupled to a switch 252. The masterunit 106 includes a laser light line generator 254 for generating alaser light that is aligned with a line of progression prior to theoperation of the computerized prosthesis alignment system 100. The laserlight line generator 254 is used in a method for aligning a prosthesis,described below. The master unit 106 includes a radio transmitter 256and/or any type of wireless communication system for transmitting andreceiving data wirelessly to and from a computer host. The wirelesscommunications protocol may be any short-range radio frequency protocol,such as Bluetooth. The master unit 106 includes a rate gyroscope 254used in calibrating the transducer 104 to a particular yaw anglesetting. The yaw angle is the deviation from a reference in thehorizontal plane. The rate gyroscope 254 is also used in the method foraligning a prosthesis. The master unit 106 further includes a centralprocessing unit 154 for data processing and/or controlling the variousother components. Additionally, the master unit 106 may include statusindicators 262, such as light-emitting diodes. The master unit 106supplies power to the transducer 104 via an input/output connector 264and additionally receives input from the transducer 104 for processingvia the central processing unit 154. The master unit 106 includes acommunications bus 266, such as for the serial communications protocolI²C, and a serial-to-peripheral interface (SPI) bus 208. The variouscomponents described above may be communicatively connected to thecentral processing unit 154 in any manner to achieve the functionalitythat will be described below.

The applications running the computerized prosthesis alignment system100 may be described in the context of computer-executable instructions,such as program modules being executed by the host computer. Generallydescribed, program modules include routines, programs, applications,objects, components, data structures and the like, that perform tasks orimplement particular abstract data types. The following descriptionprovides a general overview of a host computer system with which themethod for aligning a prosthesis may be implemented. Then, the methodfor aligning the prosthesis will be described, including the use ofapplications on the host computer. The illustrative examples providedherein are not intended to be exhaustive or to limit the invention tothe precise forms disclosed. Similarly, any steps described herein maybe interchangeable with other steps or a combination of steps or, bearranged in a different sequence in order to achieve the same result.

FIG. 11 illustrates an exemplary environment in which the computerizedprosthesis alignment system 100 may be implemented. The computerizedprosthesis alignment system 100 including the transducer 104 and masterunit 106 are coupled to a prosthesis worn by a patient 326. Theprosthetist or user 324 is available to directly communicate with thepatient 326. The computerized prosthesis alignment system 100 uses awireless modem 256 to communicate wirelessly to the host computer 300,which also includes a wireless modem 340. The user 324 may interact withthe host computer 300 that runs applications, including a gait analysisapplication and a step and phase detection application. The hostcomputer 300 uses a graphical user interface to communicate with theprosthetist 324.

FIG. 12 illustrates an exemplary host computer 300 with components thatare capable of implementing a method to align a prosthesis by conducting“gait analysis” using a gait analysis application 316 and a phase andstep detection application 317 and providing feedback to the user 324 toachieve a suitable alignment. Those skilled in the art and others willrecognize that the host computer 300 may be any one of a variety ofdevices including, but not limited to, personal computing devices,server-based computing devices, mini and mainframe computers, laptops,or other electronic devices having some type of memory. The hostcomputer 300 depicted in FIG. 12 includes a processor 302, a memory 304,a computer-readable medium drive 308 (e.g., disk drive, a hard drive,CD-ROM/DVD-ROM, etc.), that are all communicatively connected to eachother by a communication bus 310. The memory 304 generally comprisesRandom Access Memory (“RAM”), Read-Only Memory (“ROM”), flash memory,and the like. The host computer 300 also includes a display 320 and oneor more user input devices 322, such as a mouse, keyboard, etc.

As illustrated in FIG. 12, the memory 304 stores an operating system 312for controlling the general operation of the host computer 300. Theoperating system 312 may be a special purpose operating system designedfor the computerized prosthesis alignment system 100. Alternatively, theoperating system 312 may be a general purpose operating system, such asa Microsoft® operating system, a Linux operating system, or a UNIX®operating system. In any event, those skilled in the art and others willrecognize that the operating system 312 controls the operation of thehost computer 300 by, among other things, managing access to thehardware resources and input devices. For example, the operating system312 performs functions that allow a program to receive data wirelesslyover a radio receiver and/or read data from the computer-readable mediadrive 308. As described in further detail below, moment and axial loaddata in real time may be made available to the host computer 300 fromthe master unit 106 and from the computer-readable medium drive 308. Inthis regard, a program installed on the host computer 300 may interactwith the operating system 312 to process the data received from one orboth the master unit 106 and the computer-readable media drive 308.

As further depicted in FIG. 12, the memory 304 additionally storesprogram code that provides a gait analysis application 316 and a stepdetection application 317. The gait analysis application 316 includescomputer-executable instructions that, when executed by the processor302, applies an algorithm to receive, display, and process input,including moment and axial load data, to assist the user 324 in aligninga prosthesis. The gait analysis application 316, among other things,applies an algorithm to a set of moment data to correct for anyhorizontal rotational deviation of the transducer 104 during walking tothe actual line of progression and then compares the corrected data toan optimal model of alignment stored on a device 318. The step and phasedetection application 317 applies an algorithm to a set of moment andaxial data to determine if the prosthesis is being used in steady statewalking, and if it is, the algorithm differentiates each step on theprosthesis and extracts the moment data beginning each step at initialcontact and ending each step at the following initial contact in thegait cycle. Further, the step and phase detection application 317establishes if the prosthesis is either in stance or swing phase of agait cycle at each data point extracted for each step.

An overall method for aligning a prosthesis using the computerizedprosthesis alignment system 100 begins with mounting the transducer 104in the proper orientation to a prosthesis. The transducer 104 may bemounted directly at the base of the prosthesis socket 60. The invertedpyramid 110 may point up or down as needed to accommodate the setup ofthe individual prosthesis. The transducer 104 includes an anterior notch118. The anterior notch 118 is oriented to point roughly in theanticipated anterior line of progression of the patient 326. Theprosthesis is adjusted for the proper height of the patient 326 and thetransducer 104 is initially roughly aligned. The master unit 106 may nowbe coupled to the transducer 104 via the prongs 140 a and 140 b at theanterior side of the bracket 108 to establish a rigid mechanicalconnection. The plug 264 of the master unit 106 is inserted to the I/Oconnector 202 of the transducer 104 to establish electrical and datacommunication connections.

Referring to FIG. 13, a method 400 for aligning a prosthesis using thecomputerized prosthesis alignment system 100 is illustrated. The method400 begins at start block 402. From start block 402, the method 400enters block 404. In block 404, the user 324 is requested to push astart button on the master unit 106 that activates the computerizedprosthesis alignment system 100. From start block 402, the method 400enters block 406. In block 406, the computerized prosthesis alignmentsystem 100 auto initializes itself and performs a self test on thehardware including the transducer 104 and the master unit 106. Theautomatic test of the system hardware will only take about one second. Asteady amber “ready” light on the system indicates that the master unit106 and transducer 104 is okay and ready to go. From block 406, themethod 400 enters block 407. In block 407, the computerized prosthesisalignment system 100 makes a radio frequency connection to the hostcomputer 300 and the host computer's 300 software is initialized. Thehost computer 300 will automatically connect to the computerizedprosthesis alignment system 100 and perform automatic calibration of thetransducer 104. The status of the startup process may be monitored byobserving indicators on a graphical user interface appearing on the hostcomputer's display 320. In one embodiment, the master unit 106 may useBlueTooth wireless technology for automatic pairing between the masterunit 106 and the host computer 300 or any other computer running thegait analysis application 316 and the step and phase detectionapplication 317. The computerized prosthesis alignment system 100 isdesigned to signal if there is a problem. For example, an indication oflow battery power may be provided. If there are no problems, a statusindicator may turn green.

From block 407, the method 400 enters block 408. In block 408, adetermination is made whether the hardware is ready to receive user's324 input. If the determination in block 408 is no, the method 400enters block 404. In block 404, the user 324 may diagnose and fix theproblem with the hardware and/or software of the computerized prosthesisalignment system 100, and from block 409, the method 400 reenters block408. If the determination in block 408 is yes, meaning that thecomputerized prosthesis alignment system 100 is ready, the method 400enters block 410. In block 410, the computerized prosthesis alignmentsystem 100 receives input, such as “go” from the user 324 of the system100. The user 324 can then graphically push a “go” button on thegraphical user interface displayed by the host computer 300. See forexample FIG. 19, button 802, which has been activated and is now labeleda “stop” button. The host computer 300 will then start to receive liveinformation from the master unit 106. The user 324 may interact with thehost computer 300 via the graphical use interface, embodiments of whichwill be described below in association with FIGS. 19-32. From block 410,the method 400 enters block 412. In block 412, the computerizedprosthesis alignment system 100 receives input from the user 324 for theno-load base line. The no-load base line refers to the readings of thestrain gages 116 a-h from the transducer 104 measured when the patient326 is not applying any weight on the prosthesis. With the computerizedprosthesis alignment system 100 running, the patient 326 can lift theprosthesis vertically so it is slightly off the floor. The user 324 canthen zero the transducer 104 to establish the no-load base line for thetransducer 104. The user 324 interacts with the graphical user interfaceto zero the transducer 104. In one embodiment of the computerizedprosthesis alignment system 100, the system 100 may be in one of threemodes: setup mode, static mode, and dynamic mode.

The actions corresponding to each respective mode will be describedbelow. Any mode may be entered from any other mode. Modes may occursimultaneously or may be entered in series and in any order. The user324 may request, via the graphical user interface, to manually enter anymode; or upon completion of an action, any mode may be enteredautomatically, for example, by receiving a signal from a sensor, or uponcompletion of a step. In general, setup mode refers to the entry ofinput from the user 324 via the graphical user interface put up on thehost computer's 300 display 320 by the gait analysis application 316 orvia any other input entry means. Static mode generally refers to realtime monitoring of information produced from the transducer's 104 outputwhile the patient 326 is standing. In the static mode, for example, thegait analysis application 316 provides static “balance” information bysupplying live anterior/posterior and right/left socket reaction graphs.Live graphs show the past second of data. Deviation from the zero level(balanced) of each graph directly indicates balance over the prostheticfoot 20. A live weight bearing graph may also be provided and may beused as biofeedback to show the patient 326 how much of their weight isbeing supported by the prosthesis. Static mode may also includeproviding the opposite limb loading if the patient's 326 weight has beenentered at some time in the setup mode. In dynamic mode, generally, thepatient 326 will be asked to walk to measure, record and processanterior/posterior and right/left moments and perform analysis forproviding alignment information to the user 324.

Returning to FIG. 13, from block 412, the method 400 enters block 414.In block 414, the host computer 300 begins to receive data and the hostcomputer 300 plots socket reactions (moments) on the computer host'sdisplay 320. See, for example, FIGS. 20 and 21.

From block 414, the method 400 enters block 416. In block 416, the gaitanalysis application 316 receives the patient weight input. The patientweight input may be obtained via an automatic algorithm or via a manualinput from the user 324. See, for example, FIG. 22. If the patientweight input is obtained manually, i.e., the user 324 can, via agraphical user interface brought up by the gait analysis application316, enter the weight of the patient 326 and, the method 400 entersblock 420, wherein the host computer 300 begins receiving weight datafrom the transducer 104 and plotting the weight data. See, for example,FIG. 23. If the patient weight input is obtained automatically, themethod 400 enters the automatic patient weight input subroutine 500beginning in block 418.

Referring to FIG. 16, the automatic patient weight input subroutine 500begins at block 418. From block 418, the automatic patient weight inputsubroutine 500 enters block 502. In block 502, the patient 326 is askedto walk in place. From block 502, the automatic patient weight inputsubroutine 500 enters block 700. Block 700 is the step and phasedetection application 317 that can determine the start, mid-stance, andend of a single step from the initial contact of the heel to toe off theground. From the step and phase detection algorithm, the mid-stance isobtained to use in the automatic patient weight input subroutine 500.From block 700, the automatic patient weight input subroutine 500 entersblock 504. In block 504, the automatic patient weight input subroutine500 measures the axial force at the mid-stance of the step of thepatient 326. From block 504, the automatic patient weight inputsubroutine 500 enters block 506. In block 506, a determination is madewhether greater than two steps have been completed. The automaticpatient weight input subroutine 500 can keep track of the number ofsteps by counting the number of initial contacts, toe-offs, or both. Ifthe determination in block 506 is no, the automatic patient weight inputsubroutine 500 returns to block 700. If the determination in block 506is yes, the automatic patient weight input subroutine 500 enters block508. In block 508, the axial force at the mid-stance measured from morethan two steps is calculated and used in the prosthesis alignment method400 in blocks 416 or block 446 (FIG. 15).

Returning to FIG. 13, after the patient weight is input either throughmanual input or through automatic input, the method 400 enters acontinuation block 422. Continuation block 422 indicates the method 400is continued on FIG. 14.

Referring to FIG. 14, continuation block 422 from FIG. 13 is followed byblock 424. In block 424, variables for dynamic alignment are input. Thevariables may include the client identifier, the level of amputation,for example, transtibial or transfemoral, whether the left or right legis being measured, whether the inverted pyramid 110 is oriented up ordown, the transducer 104 height from the ground, the transducer 104 yawangle with respect to a line of progression during walking, etc. Thegait analysis application 316 may provide a graphical user interface forthe purpose of entering variables. See, for example, FIGS. 24 and 25.For the transducer 104 height measurement, the measurement is taken fromthe “O” ring 122 at the base of the transducer 104 to the ground withshoe. The measurement is preferred to be to the nearest five millimetersor one quarter inch.

From block 424, the method 400 enters block 426. In block 426, thetransducer angle is input. See, for example, FIG. 26. The transducerangle is a measure of yaw or horizontal deviation of the transducer 104from a predetermined line of progression. The gait analysis application316 analyzes the forces applied on the transducer 104 from the gait ofthe patient 326 in relation to the anatomical orientations ofanterior/posterior and right/left sides of the patient 326. Thetransducer 104 angle setting allows the gait analysis application 316 tointerpret the forces correctly, even if the transducer 104 is rotatedseveral degrees from the true line of progression. The transducer anglemay be input manually or via an automatic subroutine. The gait analysisapplication 316 brings up a graphical user interface for entering thetransducer angle. Clicking on a transducer angle button will open a textbox in which the user may directly enter an estimate of the rotation ofthe transducer 104 relative to a predetermined line of progression. Ifthe transducer angle is input manually, the method 400 then enters block430. For entering the transducer angle input automatically, the gaitanalysis application 316 provides a button on the graphical userinterface to select automatic transducer angle input. The user 324clicks on the button that launches a transducer angle input subroutineand the user 324 may follow the directions provided by the graphicaluser interface. The method 400 enters block 428. In block 428, themethod 400 enters the transducer angle input subroutine illustrated inFIG. 17.

Referring to FIG. 17, from block 428 of FIG. 14, the transducer angleinput subroutine 600 enters block 602. In block 602, the computerizedprosthesis alignment system 100, and in particular, the master unit 106projects a laser line with the laser line generator 254 on the floor.Alternatively, the laser generator 254 may project a beam or spot. Thelaser line generator 254 may be factory aligned with the bracket 108 sothat when attached to the transducer 104 and enabled by the gaitanalysis application 316, the laser line generator 254 projects thelaser line onto the floor behind the patient 326 and parallel to theanterior/posterior plane of the transducer 104. The prosthesis withtransducer 104 is rotated to align the laser with the predetermined lineof progression of walking. With the transducer 104 so oriented, the rategyroscope's 258 output is nulled on this heading. The line ofprogression may be any straight line on the ground or floor over whichthe patient 326 will be instructed to walk. Floor tile edges or apattern in a carpet can provide a suitable line of progression. With thelaser line projected on the intended line of progression, the user 234pushes the start button on the master unit 106. The patient 326 is theninstructed to walk along the line of progression and the gyroscope 258output is sampled at mid-stance at one or more steps. The rate gyroscope258 in the master unit 106 will track the rate of angle rotation witheach step. This output signal from the rate gyroscope 258, whenintegrated over time represents the angle of the transducer 104 withrespect to the line of progression which provides a correction factorneeded to calculate the moments in the anterior/posterior and right/leftplanes. The correction may be done by physically rotating the transducer104 as indicated by the calculated correction factor or by amathematical correction applied to the transducer's 104 output signals.

From block 602, the transducer angle input subroutine 600 enters block700. Block 700 is the step and phase detection application 317. From thestep and phase detection application 317, the transducer angle inputsubroutine 600 utilizes input of the midstance of a step. From block700, the transducer angle input subroutine 600 enters block 604. Inblock 604, the computerized prosthesis alignment system 100 determinesthe yaw from the rate gyroscope 258 at midstance to determine thedeviation from the line of progression. This measurement is thetransducer angle input. From block 604, the transducer angle inputsubroutine 600 enters block 606. In block 606, a determination is madewhether greater than two steps have been completed. If the determinationin block 606 is no, the transducer angle input subroutine 600 reentersblock 700 to return to the step detection algorithm, and repeats untilgreater than two steps are completed. If the determination in block 606is yes, the transducer angle input subroutine 600 enters block 608,wherein the laser line automatically turns off, indicating that thetransducer angle measurement is complete and the transducer angle isinput to block 426 (FIG. 14) and may also be used in block 446 (FIG.15). The transducer angle input and/or any other setup information maybe stored in the onboard memory 208 of the transducer 104 or in anyother memory, such as memory 304 of the host computer 300.

From the transducer angle input subroutine 600, the method 400 returnsto FIG. 14. From the sensor angle input block 426, the method 400 entersblock 430. In block 430, the method 400 initializes the gait variablesand starts data streaming to the host computer 300. At this point in theprosthesis alignment method 400, the gait analysis application 316 maybring up a graphical user interface providing the user 324 withselection buttons including: go/stop, new, analyze, and save. See, forexample, FIG. 19. Generally, the user 324 is prepared to select the gobutton to allow streaming data from the computerized prosthesisalignment system 100 to the gait analysis application 316. While thedata are streaming, the graphical user interface labels the button as astop button. The graphical user interface may provide a data indicatorto monitor the status, for example, an amber light if data collection ispaused, and a green light if data is being streamed continuously.

Data for analysis is preferably collected from a continuous steppingsession during which the patient 326 does not pause or otherwiseinterrupt the flow of data for a minimum number of steps. Preferablytoo, the data for analysis is collected from a continuous steppingsession so that any acceleration and deceleration effects are minimizedwhen walking. A suitable continuous stepping session includes at least 3steps in series, but need not be greater than 6 steps during any onecontinuous stepping session. Alternatively, at least 2 steps may beused. The step and phase detection algorithm 700 is employed todetermine the start and stop of each step to count the number of stepsduring the session, and also to determine the midstance of each step forcalculation of the axial load indicative of the weight bearing on theprosthesis. By using the readings of anterior/posterior moment,right/left moment, and axial force, the step and phase application 317is able to identify the gait cycle, the stance and swing phase of eachfoot, and determine whether continuous stepping is occurring. Thiscollection of data is described in FIG. 14 as blocks 700, 434, 436, and438. From block 430, the method 400 enters block 700. Block 700 is thestep and phase detection application once again that is illustrated inFIG. 18. From block 700, the method 400 enters block 434. Block 434 isfor determining whether continuous stepping is occurring by receivinginformation from the step and phase detection application 317. If thedetermination in block 434 is no, the method 400 returns to block 700,the step and phase detection application 317. If the determination inblock 434 is yes, the method 400 enters block 436. In block 436, themethod 400 determines whether greater than three steps have beencompleted. If the determination in block 436 is no, the method 400returns to block 700, the step and phase detection application 317. Ifthe determination in block 436 is yes, the method 400 enters block 438.In block 438, the method 400 determines whether greater than six stepshave been completed. If the determination in block 438 is no, the method400 returns to block 700, the step and phase detection application 317.If the determination in block 438 is yes, the method 400 enters acontinuation block 440. Continuation block 440 indicates that method 400is continued in FIG. 15.

Referring to FIG. 15, from continuation block 440, the method 400 entersblock 444. After collecting data, the gait analysis application 316awaits the user's 324 input. Block 444 is for receiving input from theuser 342. The gait analysis application 316 brings up a graphical userinterface for providing options for the user 324. See, for example, FIG.19. The graphical user interface may have “save,” “analyze,” and “new”buttons that the user 324 may select to save data, analyze data, orperform new data collection. If the user selects the new button, thegait analysis is based on a series of continuous steps that are selectedby the gait analysis application 316 automatically. The user 324 mayclick on the new button to start collecting a new series of steps.Generally, the user 324 will click on the new button in the secondsbefore the patient 326 starts to walk. The new button is also selectedwhenever a change has been made to the alignment and the user 324 wouldlike to measure with the realigned transducer 104. If the user 324clicks on the save button, all, some, or none of the data can be savedto memory. At that point, the user 324 may start a new session byclicking on the new button so that the gait analysis application 316then starts looking for a “new” series of steps to record once thepatient 326 starts walking again. Once six steps have been recorded, thegait analysis application 316 will not add additional steps to theseries. This limit of steps is variable, six being merely representativeof one embodiment. The gait analysis application 316 may set a conditionon whether to enable the analyze button. For example, the gait analysisapplication 316 may enable the analyze button when a minimum number ofcontinuous steps are collected in series. A suitable number for analysisis four, but fewer or more steps may also be used.

In the method 400, from block 444, one of three blocks may be entered.From block 444, if the input to block 444 is “save,” the method 400enters block 448. In block 448, the method 400 saves into a data file,data collected from steps 2 to n−1. If the input in block 444 is “new,”the method 400 returns via continuation block 442 to FIG. 14. Referringto FIG. 14, from continuation block 442, the method 400 returns to block430 for initialization of the gait variables and starts data streamingonce again. If the input in block 444 is “analyze,” the method 400enters block 446. In block 446, the method 400, calculates gaitvariables from the yaw-corrected data using input from the transducerangle calculation in FIG. 17, and the patient weight in FIG. 16. Fromblock 446, the method 400 enters block 450. In block 450, the method 400calculates the prosthesis misalignment. The gait analysis application316 analyzes the patient's gait relative to an advanced mathematicalmodel 318 of an ideal or optimal gait stored in the host computer device300. The gait analysis application 316 determines the alignment changethat would move the present alignment toward the model. For example, oneembodiment for calculating the prosthesis misalignment may be to compareone or more of the gait variables collected during the walking sessionof the current patient 326 against the alignment model calculated from alarger database of gait variables collected from multiple and differentpatients from numerous prior sessions and stored in the device of thehost computer 300. From block 450, the method 400 enters block 454. Inblock 454, the method 400 determines whether the present alignment isoptimal by performing a comparison of the gait variables for the presentsession as compared with the stored alignment model 318. The alignmentmodel block 452 supplies the alignment model to block 450 to determinemisalignment.

To analyze for the misalignment, in one embodiment, the gait analysisapplication 316 calculates for each individual step, certain “gait”variables. Gait variables may include, but are not limited to some orall of, the anterior/posterior moment and right/left moment at each 20percent increment in time of the stance phase from 0% to 100%; themaxima and minima of the anterior/posterior moment and right/left momentfor the first and the last 50% of the stance phase; the slope of thechange in anterior/posterior moment and right/left moment during eachsuccessive 20% time increment; and the integrated anterior/posteriormoment and right/left moment measured over the period of each stancephase. The gait variables are then applied to a predefined model ofalignment. The equations used in deriving the model of alignment arederived heuristically to minimize an external criterion called thePrediction Error Sum of Squares, or PESS, for previously measured socketreaction moments and axial force with a known set of geometricmisalignments.

${PESS} = {\frac{1}{N}{\sum\limits_{t = 1}^{N}\left( {y_{y} - {f\left( {x_{t},{\hat{a}}_{t}} \right)}} \right)^{2}}}$

Where N is the number of gait variable samples available, y is thetarget geometric misalignment, and â is an estimation of the combinedparameters that describe the misalignment. The equation derivations areachieved using the Group Method of Data Handling described by Madala andIvakhnenko (Madala, H., and Ivakhnenko, A., “Inductive LearningAlgorithms for Complex Systems Modeling,” CRC Press, Boca Raton, Fla.,USA, 1994). Solving the derived model equations with the gait variablescalculated from the computerized prosthesis alignment system 100 data,results in a numeric estimation of the geometric misalignment in theprosthesis measured. For robustness, estimations from each of theequations becomes a vote added to a more generalized estimation of themisalignment.

Returning to FIG. 15, if the determination in block 454 is no, meaningthat the alignment is not optimal, the method 400 enters block 456. Inblock 456, from the misalignment calculations described above, the gaitanalysis application 316 may provide verbal, textual, or graphicinstructions to the user 324 as to which set screws 117 to loosen ortighten and to which side to move the transducer 104 to make theprosthesis alignment of the patient 326 similar to the optimal storedalignment model from block 452. Such corrective action can be providedto a user 324 via the host computer's 300 display 320 or, alternatively,the computerized prosthesis alignment system 100 may issue verbalinstructions. See, for example, FIG. 27.

From block 456, the method 400 enters block 462. In block 462, the user324 manually adjusts the alignment of the transducer 104 by adjustingthe particular set screws 117 as instructed in block 456 and making thealignment of the transducer 104 in the anterior/posterior or right/leftplanes as provided by the instructions. From block 462, the method 400enters block 444, where the user can save, analyze, or start a new datacollection trial.

If the determination in block 454 is yes, meaning that the alignment isoptimal, the method 400 enters block 458. In block 458, the method 400indicates to the user 324 that the alignment of the prosthesis isoptimal and no further corrections are necessary. From block 458, themethod 400 enters block 460, where the method 400 stops.

When the user 324 has completed the dynamic alignment process using thecomputerized prosthesis alignment system 100, the user 324 can replacethe transducer 104 with a substitute pyramid adaptor 105 seen in FIG. 5.The substitute pyramid adaptor 105 fits within the envelope of thetransducer 104. The substitute pyramid adaptor 105 is the same height ofthe transducer 104, so that when the substitute pyramid adaptor 105 issubstituted for the transducer 104, the alignment is retained. Thetransducer 104 may fit within the physical envelope of a conventionalpyramid adaptor, so that the transducer 104 can be substituted with thesubstitute pyramid adaptor 105 having substantially similar dimensionsas the transducer 104, so as not to alter the alignment achieved withthe transducer 104. To swap the transducer 104 with the substitutepyramid adaptor 105, the user 324 marks the anterior notch 118 positionon the prosthesis socket 60. The user 324 removes two adjacent alignmentset screws 117 (for example, anterior and left) that hold the invertedpyramid 110 of the transducer 104. The transducer 104 may now bedecoupled from the tube clamp adaptor 40. The four bolts in the slots126 are removed to decouple the transducer 104 from the prosthesissocket 60. The substitute pyramid adaptor 105 is substituted for thetransducer 104. The substitute pyramid adaptor 105 similarly includes ananterior notch. The anterior notch on the substitute pyramid adaptor 105is matched with the mark made on the prosthesis socket 60. Thereafter,the four bolts attaching the pyramid adaptor 105 to the prosthesissocket 60 are replaced and the two adjacent set screws 117 that werepreviously removed are reinserted and tightened. The prosthesis nowretains the same alignment that was achieved using the computerizedprosthesis alignment system 100.

Alternatively, in another embodiment, the transducer 104 may remainincorporated in the prosthesis and the patient 326 may use theprosthesis with the included transducer 104 in the normal course ofwalking for an extended period of time. During such extended period oftime, the transducer 104 may continuously or semi-continuously recordthe socket reactions, i.e., the anterior/posterior, right/left moments,axial force, and any other data and store the information in the onboardmemory 208. At a later time, the information from the onboard memory 208may be retrieved and analyzed.

Before a description of the step and phase detection application 317,several terms need to be understood. A gait cycle is a repeat unit ofthe walking motion, for example, from initial contact of the heel of onefoot to the subsequent initial contact of the heel of the same foot. Thegait cycle of one foot includes a stance phase when the foot is incontact with the ground. The gait cycle includes a swing phase when thefoot is not in contact with the ground. Initial contact is the start ofthe stance phase when the heel makes contact with the ground. Toe-off isthe end of the stance phase when the toe leaves the ground. The swingphase occurs after toe-off and before initial contact of the heel. Oneswing phase and one stance phase complete a gait cycle.

Referring to FIG. 18, a flow diagram for the step and phase detectionapplication 317 is illustrated. The step and phase detection applicationwill be described in the context of a method 700. Generally described,the step and phase detection application 317 provides for real timeanalysis of the stream of moment and axial load data from the prosthesisalignment system 100 as discrete individual steps and by the phases(stance and swing) of gait of each step. The step and phase detectionalgorithm 700 provides for real time analysis of the stream of momentsand axial load data from the prosthesis alignment system 100 as discreteindividual steps taken during continuous walking and by the phases ofgait of each step. The method 200 begins at block 702. In block 702, themethod obtains a stream of moment and axial force data samples from thecomputerized prosthesis alignment system 100. From block 702, the method700 enters block 704. In block 704, a determination is made whether theelapsed times of the initial contact and toe-off of steps are withinacceptable ranges to define continuous walking. For example, each newdata sample is evaluated first for the amount of time since the onset ofboth the last and the current weight bearing step. If the elapsed timesare neither too long, indicating either standing or slow walking, or tooshort, indicating running, then the program enters block 708. If theelapsed time from the initial contact of the current step is too long ortoo short, then the data sample is considered to not be from steadystate walking, and the method enters block 706 where the sample and anypending phase of gait indices are removed from memory. If thedetermination in block 704 is yes, the method 700 enters block 708. Inblock 708, the method 700 determines whether the prosthesis axial loadis greater than a threshold which would occur without ambulation. If thedetermination is yes, then the data sample is considered to be within astance phase of gait and the method 700 enters block 712. If thedetermination is no, the method 700 considers the data sample to be fromthe swing phase of gait and the method 700 enters block 710. In block712, if the data sample is the first stance sample of the step, then thedata sample is indexed as the initial contact time in block 718,otherwise the sample is the last stance sample and is indexed as toe-offtemporarily in block 714. Thereafter, each successive stance data samplewill take the index of the toe-off sample in block 714 and calculate theelapsed time in block 714 and add the data sample to a buffer for thecurrent step stance phase until the algorithm determines that the stepis in swing phase once again. On the next occurrence of the first datasample being evaluated in stance phase (Initial Contact), the completionof the previous step is noted by transferring the stance and swing phasedata buffers to an indexed array of complete individual steps and phaseindices in block 720. This facilitates further analysis by the gaitanalysis application 316 by permanently storing the data on the computerreadable medium in block 722.

For example, the step and phase detection application 317 may set alower threshold of axial force below which, the stance phase isconsidered to not be occurring. If the determination in block 708 is no,the method 700 enters block 710. In block 710, the method 700 adds thedata sample to a buffer and identifies it as a swing phase for thecurrent step. If the determination in block 708 is yes, the method 700enters block 712. In block 712, a determination is made whether the datasample is the first for the current step. Data samples can stream atseveral times per second so that for each step, the step is composed ofseveral data samples. The data sample identifying the start of thestance phase is determined by the step and phase detection application317. For example, by determining when the axial force is above athreshold. If the determination in block 712 is no, the method 700enters block 714. In block 714, the method increments the index of adata sample for the time of toe-off. From block 714, the method 700enters block 716.

If the determination in block 712 is yes, the method 700 enters block718. In block 718, the data sample is indexed and identified with thetime of initial contact.

From block 718, the method 700 may enter block 716 or block 720. Block720 is entered when beginning a new step. The data from the previousstep is saved. In block 720, the method 700 transfers buffered datasamples from the previous walking step to permanent storage. From block720, the method 700 enters block 722. In block 722, the method storesthe data for the completed walking steps.

Otherwise, the method 700 enters block 716. In block 716, the method 700calculates the elapsed time from the present and the previous initialcontacts. From block 716, the method enters block 724. In block 724, themethod 700 adds the data sample to a buffer for the current step andstance phase.

The gait analysis application 316 includes a graphical user interfacefor interacting with the user 324. Embodiments of the graphical userinterface are illustrated in FIGS. 19-32.

FIG. 19 illustrates a graphical user interface 800 provided by the gaitanalysis application 316 for use in block 410 of method 400 in FIG. 13.The graphical user interface 800 provides to the user 324, the option toselect from four buttons, including a go/stop button 802, a new button804, an analyze button 806, and a save button 808. The graphical userinterface 800 also includes a drop down menu 812 for selecting thenumber of steps to plot and a label 810 and text box showing the numberof usable steps during streaming. The graphical user interface 800 alsoincludes a check box 814 and label 816. The label 816 identifies thecheck box 814 is for auto scaling the plots of the moments. By clickingon the auto scale checkbox 814, the user 324 can automatically scale thegraphs to a suitable range.

FIG. 20 is an illustration of a graph 818 of the right/left momentplotted for a stance phase from initial contact to toe-off for use inblock 414 of method 400 in FIG. 13. A stance phase begins with initialcontact (IC) of the heel with the ground and ends with toe off (TO) theground. At the middle of the stance phase is the midstance (MSt). One ormore stance phases can be plotted at a time on the graph. From theillustration, the graph indicates that the moment is generally negative.A rapid increase and decrease in negative moment from initial contact tomidstance is noticed, followed by a gradual decline in moment.

FIG. 21 is an illustration of a graph 820 of the anterior/posteriormoment plotted for a stance phase for various steps for use in block 414of method 400 in FIG. 13. From the illustration, there is an initialrelatively small negative moment, followed by a rapid increase in momentat a point about half-way to the mid-stance and continuing past themid-stance to reach a maximum at a point about half-way from mid-stanceto toe-off, and followed by a rapid decline thereafter to toe-off.

FIG. 22 is an illustration of a graphical user interface 822 forentering the patient 326 weight for block 416 of method 400 in FIG. 13.The graphical user interface 822 includes a text box 824 for providinginstructions on entering the weight of the patient 326. The graphicaluser interface 822 includes a text box 826 for manually entering theweight of the patient 326. The graphical user interface 822 includes aweigh patient button 828 for automatically entering the weight of thepatient 326. Clicking on the weigh patient button 828 calls up theautomatic patient weight input subroutine 500 (FIG. 16). The graphicaluser interface 822 has a cancel button 830 and a done button 832.Clicking on the cancel button 830 closes the graphical user interface822 without entering the patient 326 weight. Clicking on the done button832 enters the patient 326 weight in the gait analysis application 316and/or in the onboard memory 208 of the transducer 104 and may close thegraphical user interface 822.

FIG. 23 is an illustration of a graphical user interface and bar graph834 showing patient 326 weight information for block 420 of method 400in FIG. 13. The bar graph 834 graphs the percent of the patient 326weight supported by the prosthesis (PRO) and the opposite foot (OPP).The graphical user interface 834 includes a percent body weight (BW)checkbox 836. Clicking on the percent body weight checkbox 836 will showthe information as a percentage of body weight. Specifically, FIG. 23illustrates that the prosthesis bears slightly less than 50% of the bodyweight of the patient 326 during walking, and the opposite foot bearsslightly greater than 50% of the body weight of the patient 236.

FIG. 24 is an illustration of a graphical user interface 838 forentering variables for dynamic alignment for block 424 of method 400 inFIG. 14. The graphical user interface 838 includes a button 840 forzeroing the transducer 104. The graphical user interface 838 includes atext box 842 for entering a client identifier. The graphical userinterface 838 includes a text box 844 for entering the type ofamputation, such as transtibial or transfemoral. The graphical userinterface 838 includes a text box 846 for entering whether theprosthesis is for the left or the right leg. The graphical userinterface 838 includes a label 856 and text box 848 for entering whetherthe inverted pyramid 110 is pointing in the down or up configuration.The graphical user interface 838 includes a label 858 and text box 850for entering the height of the transducer 104. The graphical userinterface 838 includes a label 860 and text box 852 for manuallyentering the transducer angle. The graphical user interface 838 includesa label 862 and text box 854 for manually entering the weight of thepatient 326.

FIG. 25 is an illustration of another embodiment of a graphical userinterface 864 for input entry for block 424 of method 400 in FIG. 14.The graphical user interface 864 includes a label 866 and dropdown menu870 for selecting the level of the prosthesis, such as transtibial ortransfemoral. The graphical user interface 864 includes a label 868 anddropdown menu 872 for selecting either the left or the right sidecorresponding to the amputation. The graphical user interface 864includes radio buttons 874 and 876 for selecting whether the invertedpyramid 110 is configured in the up or the down direction. Selecting oneradio button removes the selection of the other radio button. Thegraphical user interface 864 includes a label 880 and text box 878 formanually entering the height of the transducer 104 from the floor. Thelabel 880 gives directions on measuring the height. The graphical userinterface 864 includes a cancel button 882 and a done button 884.Clicking on the cancel button 882 closes the graphical user interface822 without entering the setup information. Clicking on the done button832 enters the setup information in the gait analysis application 316and/or in the onboard memory 208 of the transducer 104 and may close thegraphical user interface 864.

FIG. 26 is an illustration of a graphical user interface 885 forentering the transducer angle for block 426 of method 400 in FIG. 14.The graphical user interface 885 includes a label 886 for providinginstructions to enter transducer angle manually or automatically. Thegraphical user interface 885 includes a label 890 and text box 888 formanually entering the degrees of yaw with respect to a predeterminedline of progression. The graphical user interface 885 includes an automeasure button 892 for automatically measuring the yaw angle withrespect to the predetermined line of progression. Clicking on the automeasure button 892 calls the transducer angle input subroutine of FIG.17. The graphical user interface 885 includes a cancel button 894 and adone button 896. Clicking on the cancel button 894 closes the graphicaluser interface 885 without entering the transducer angle information.Clicking on the done button 896 enters the sensor angle information inthe gait analysis application 316 and/or in the onboard memory 208 ofthe transducer 104 and may close the graphical user interface 885.

FIG. 27 is an illustration of a graphical user interface 898 for block456 of the gait analysis application 316 of FIG. 12. The graphical userinterface 898 includes a progress bar 900 for indicating the progress ofthe analysis. When the analysis is complete, the progress bar 900 isfull. The graphical user interface 898 includes a first label 902 and asecond label 904. The label 902 provides to the user 324, the alignmentcondition in the anterior/posterior plane and instructions for aligningthe prosthesis in the anterior/posterior plane by identifying the setscrew 117 or screws needing adjustment, and the amount of turns that areto be applied to the set screws 117. The label 904 provides to the user324, the alignment condition in the right/left plane and instructionsfor aligning the prosthesis in the right/left plane by identifying theset screw 117 or screws needing adjustment, and the amount of turns thatare to be applied to the set screws 117. The graphical user interface898 includes a video button 906 and a done button 908. Clicking on thevideo button 906 brings up a video of a model patient 326 walking withthe detected misalignment. Clicking on the done button 908 may close thegraphical user interface 898.

FIGS. 28, 29, and 30 represent an alternative graphical user interfacefor the gait analysis application 316, including three modes ofoperation.

FIG. 28 is an illustration of a graphical user interface 1000 for thegait analysis application 316 depicting three modes of operation for thecomputerized prosthesis alignment system 100. The modes include thesetup 1024 mode, static 1026 mode, and dynamic 1028 mode. FIG. 28illustrates the setup mode 1024. The graphical user interface 1000includes a “go” button 1002, a “new” button 1004, an “analyze” button1008, and a “zero transducer” button 1010. In the setup mode 1024, thego button 1002, new button 1004, save button 1006, analyze button 1008,and zero sensor button 1010 are inactive. The graphical user interface1000 presents to the user 324, a drop down menu 1012 for selecting therate of updating the data. The graphical user interface 1000 includes alabel and check box 1014 for auto scaling. Checking the check box 1014causes the graphs showing the data in real time to provide a suitablerange. The graphical user interface 1000 includes a label and text box1030 for entering the client ID. The graphical user interface 1000includes a label and text box 1032 for manually entering the weight ofthe patient 326. The graphical user interface 1000 includes a label anddrop down menu 1034 for entering the level of the amputation. Forexample, the user 324 may select from the dropdown menu 1034,transtibial or transfemoral. The graphical user interface 1000 includesa label and dropdown menu 1036 for entering whether the prosthesis is aleft or right prosthesis. The graphical user interface 1000 includes alabel and text box 1038 for manually entering the height of thetransducer 104. The graphical user interface 1000 includes a label and apair of radio buttons 1040 and 1042. The user 324 selects radio button1040 when the configuration of the inverted pyramid 110 points up. Theuser 324 selects radio button 1042 when the orientation of the invertedpyramid 110 points down. The graphical user interface 1000 includes alabel and text box 1044 for manually entering the transducer angledeviation from a predetermined line of progression. The graphical userinterface 1000 includes a status indicator 1016 to monitor the status ofthe master unit 106, a status indicator 1018 to monitor the status ofthe transducer 1018, and a status indicator 1020 to monitor whether datais streaming. The graphical user interface 1000 also monitors thebattery condition with the battery condition status bar 1022. In thesetup mode 1024, the master unit 106 is active, but not transmitting;the transducer 104 is in a ready mode; and data streaming is notoccurring.

FIG. 29 is an illustration of a graphical user interface 1050 for thestatic mode 1026 of the computerized prosthesis alignment system 100. Inthe static mode 1026, the go button 1002 is active, but has been changedinto a “stop” button 1002 after its activation. The new button 1004, andthe zero transducer button 1010 are active. The save button 1006 and theanalyze button 1008 are inactive. The graphical user interface 1000presents to the user 324, a drop down menu 1012 for selecting the rateof updating the data. The graphical user interface 1000 includes a labeland check box 1014 for auto scaling. Checking the check box 1014 causesthe graphs showing the data in real time to provide a suitable range. Inthe static mode 1026, the user 324 is presented with a weightdistribution graph 1052 and a socket moment graph 1054. The weightdistribution graph 1052 can show the percent of the total weight beingsupported by the prosthesis 1062 (Pro) and the opposite foot 1064 (Opp),or the user 324 can modify the labels to show the relative percentagesof the weight being supported by the prosthesis and opposite leg. Theuser 324 selects weight in pounds or weight percent by using thedropdown menu 1056.

The socket moment graph 1054 is a chart having a centroid 1066 and alocus 1056 indicating the direction and magnitude of the moments actingon the prosthesis socket 60. The centroid 1066 does not represent theabsence of all moment, but rather, the centroid 1066 represents anoptimal alignment that may include some amount of anterior/posteriormoment and right/left moment acting on the prosthesis socket 60 evenwhen the locus is over the centroid 1066. The socket moment graph 1054is oriented so that the top correlates to the anterior side of theprosthesis socket 60, the bottom of the graph 1054 correlates to theposterior side of the prosthesis socket 60, the right of the graph 1054correlates to the right side of the prosthesis socket 60, and the leftof the graph 1054 correlates to the left side of the prosthesis socket60. The object of the socket moment graph 1054 is to allow the user 324to align the locus 1056 over the centroid 1066 and thus achieve theoptimal static alignment. As mentioned before, the centroid 1066 may notcorrespond with zero moment, but rather, an optimal setting that mayinclude some moment in the anterior/posterior plane and also in theright/left plane. Accordingly, because the centroid 1066 may actuallyrepresent some moment in both planes, the user 324 may apply an anteriorbias 1058 and a left bias 1066 so that the centroid 1066 can actually beplaced in the center of the graph 1054 to correspond to the optimalsetting even when moments are present in both planes.

In another embodiment of the static mode, as illustrated in FIG. 31, agraphical user interface 1200 is presented to the user 324 including twographs representing the anterior/posterior plane 1210, and theright/left plane 1212. Each graph includes a ball 1204, 1224 at the endof a line 1206, 1226 plotted in the center of a target 1208, 1228 thatindicates points of balance of moments measured by the transducer 104.The height of the line 1206, 1208 may represent the axial force. Whenthe patient 326 is balanced evenly on each foot, the height of the lines1206, 1226 should be at the height of the center of the targets 1208,1228 (half body weight). The displacement of the lines 1206, 1226 to theleft or right of the targets 1208, 1228 represents the moment beingmeasured in that plane. The graphical user interface 1200 includes atext dialog box 1214 for the graph 1212, and a text box 1216 for thegraph 1210. As the user 324 makes an alignment adjustment that issuggested in the text box below each graph, the balls 1204, 1224 on thelines 1206, 1226 should move toward the targets 1208, 1228. A graphicaluser interface, as described, may appeal to a user 324 because itpresents the information in a manner similar to how they are trained toalign a prosthesis. The lines 1208, 1228 are similar to the “load line”commonly used to do bench alignment.

FIG. 30 is an illustration of a graphical user interface 1100 for thedynamic mode 1028 of the computerized prosthesis alignment system 100.In the dynamic mode, the go/stop button 1002, new button 1004, savebutton 1006, analyze button 1008, and zero transducer button 1010 areactive. The save button 1006 and the analyze button become active afterselecting the new button 1004. The graphical user interface 1100includes a dropdown menu 1012 for providing to the user 324, the optionof selecting the number of steps to plot. The graphical user interface1100 includes a label and check box 1014 for auto scaling. Checking thecheck box 1014 causes the graphs showing the data in real time toprovide a suitable range.

In the dynamic mode 1028 of the computerized prosthesis alignment system100, the graphical user interface 1100 presents to the user 324, a firstgraph 1070 showing moments in the anterior/posterior plane. The graph1070 may include plots 1076 and 1078 for various steps selected by theuser 324 from the dropdown menu 1012. The graph 1070 includes an optimalmoment curve 1072 that includes an upper and a lower limit. The user 324may make alignment adjustments to fit the step plots within the upperand lower limits of the optimal moment curve 1072. In the dynamic mode1028 of the computerized prosthesis alignment system 100, the graphicaluser interface 1100 presents to the user 324, a second graph 1084showing moment in the right/left plane. The graph 1084 may include plots1086 and 1088 for various steps selected by the user 324 from thedropdown menu 1012. The graph 1084 includes an optimal moment curve 1090that includes a right and left limit. The user 324 may make alignmentadjustments to fit the step plots within the right and left limits ofthe optimal moment curve 1090. The graphical user interface 1100includes the yaw angle 1092 with respect to the predetermined line ofprogression. The user 324 may select to track the angle or not track theangle by checking or unchecking the checkbox 1094. The graphical userinterface 1100 includes a stance chart 1080. The stance chart 1080 maybe a bar chart or include text. The stance chart 1080 indicates how muchof the weight is being supported by the prosthesis and the opposite footfor the selected steps. For example, in step number 2, the prosthesissupported 41% of the body weight, while the opposite foot supported 59%of the body weight. In step No. 3, the prosthesis supported 42% of thebody weight, while the opposite foot supported 58% of the body weight.Algorithms can be used to determine when to start measuring the weight,for example, if the transducer 104 notices the axial force greater thanor equivalent to a threshold, the gait analysis application 316 mayassume that the stance phase is in progress and then attribute the axialforce beginning at the threshold until the axial force diminishes tobelow a threshold. The weight on the prosthesis is subtracted from thetotal body weight to calculate the weight on the opposite foot.

Another embodiment of a graphical user interface 1300 for the dynamicmode is illustrated in FIG. 32. The graphical user interface 1300presents to the user 324 a coordinate graph system 1302 where a squarecursor 1304 represents the translation of the limb, and a triangularcursor 1306 represents the angulation. The center 1308 of the coordinategraph system (the target) represents the ideal alignment. The goal is tomove the cursors 1304, 1306 toward the center 1308 based on the textbased feedback provided in the text box 1310. Specific alignmentfeedback may be generated in textual form, such as instructions to theuser 324 for angular and translational alignment changes to bring theprosthesis socket 60 closer to the center 1308 of the coordinate system1302.

While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the invention.

1. A transducer, comprising: a transducer body; an adaptor on thetransducer body for coupling to a prosthesis; first and secondstrain-measuring devices positioned, respectively, on anterior andposterior sides of the adaptor to measure forces in a first plane; andthird and fourth strain-measuring devices positioned, respectively, onright and left sides of the adaptor to measure forces in a second planesubstantially orthogonal to the first plane; wherein the first and thesecond strain-measuring devices and the third and the fourthstrain-measuring devices are arranged to measure right/left andanterior/posterior bending moments and reduce measuring forces in athird plane orthogonal to the first and second planes.
 2. The transducerof claim 1, wherein the first plane is the anterior/posterior plane, thesecond plane is the right/left plane, and the third plane is thetransverse plane.
 3. The transducer of claim 1, further comprising aload-bearing member disposed over the first and second strain-measuringdevices.
 4. The transducer of claim 1, comprising fifth, sixth, seventhand eighth strain-measuring devices, wherein a pair of strain-measuringdevices is provided on each of the anterior, posterior, right, and leftsides of the transducer.
 5. The transducer of claim 1, comprising a beamdisposed on each of the anterior, posterior, right and left sides,wherein the beams support the adaptor.
 6. The transducer of claim 1,comprising a beam disposed on each of the anterior, posterior, right andleft sides, wherein the beams support the adaptor, each beam having astrain-measuring device positioned on at least two opposite sidesurfaces of each beam.
 7. The transducer of claim 1, wherein the adaptoris an inverted pyramid.
 8. The transducer of claim 1, wherein thetransducer body comprises a beam aligned in the anterior/posteriorplane.
 9. The transducer of claim 1, wherein the transducer bodycomprises a beam aligned in the right/left plane.
 10. The transducer ofclaim 1, further comprising memory to store data.
 11. The transducer ofclaim 1, comprising a first and a second strain gage on a beam on theanterior side, a third and fourth strain gage on a beam on the posteriorside, a fifth and sixth strain gage on a beam on the right side, and aseventh and eighth strain gage on a beam on the left side.
 12. Thetransducer of claim 11, wherein two sets of four strain gages is eacharranged in a balanced bridge, and each balanced bridge produces avoltage output representative of a moment in a plane.
 13. The transducerof claim 12, further comprising amplification circuits for amplifyingthe output from the balanced bridges and an analog-to-digital conversioncircuit that receives the amplified output from the balanced bridges.14. The transducer of claim 13, further comprising a digital-to-analogconversion circuit connected to the amplification circuit of eachbalanced bridge to apply an offset voltage to calibrate the output fromthe amplification circuit.
 15. The transducer of claim 1, furthercomprising circuitry to measure the axial load on the transducer.
 16. Atransducer for coupling to a prosthesis, comprising: a transducer body;an adaptor on the transducer body for coupling to a prosthesis; meansfor measuring moments in the anterior/posterior plane and the right/leftplane, and reducing measuring moments in the transverse plane, whereinsaid means comprises first and second strain-measuring devicespositioned, respectively, on anterior and posterior sides of the adaptorand third and fourth strain-measuring devices positioned, respectively,on right and left sides of the adaptor.